1. Field of the Invention
The present invention relates to a control circuit for liquid crystal rear-vision mirror and particularly to a control circuit for operating the liquid crystal rear-vision mirror having one-dotted display device for use in an automobile.
2. General Description of the Prior Art
A liquid crystal display device includes two pieces of glass-substrate coated with transparent electrodes and a liquid crystal material filled up between the two substrates. On the liquid crystal display cell a desired pattern to display is etched and a voltage is fed to said transparent electrodes to operate a liquid crystal shutter, thereby making the pattern be displayed. There is required a liquid crystal driving circuit for feeding a predetermined voltage to the liquid crystal cell to make the etched pattern be displayed as desired.
As the liquid crystal cell now becomes widely used in the field, a liquid crystal rear-view mirror is now being introduced into the automobile. The mirror comprises a singly formed one-dotted liquid crystal display cell having a reflecting film made by aluminium evaporation. But it is almost impossible in the conventional liquid crystal driving circuit to make the one-dotted liquid crystal rear-vision mirror installed in an automobile operate to promote the convenience of a driver by controlling the liquid crystal shutter in response to the incident light.
3. Object of the Invention
Thus the main object of the present invention is to provide a control circuit for a liquid crystal rear-vision mirror for use in an automobile. It is another object to provide a control circuit capable of automatically operating the liquid crystal rear-vision mirror to prevent the incident light from being reflected toward the driver whenever the amount of light reaches beyond a fixed reference level.
The other object of the present invention is to provide a voltage driving circuit being capable of quickly operating the liquid crystal rear-vision mirror by buffering the driving voltage of the liquid crystal at a sufficiently high level.